This invention relates to an apparatus and method used in oil and gas well bores. More particularly, but not by way of limitation, this invention relates to an apparatus and method used in the pressure testing of reservoirs.
In the drilling and production of hydrocarbon reservoirs, operators will find it necessary to periodically obtain static and flowing pressures of the reservoir. This information is necessary for reservoir management in order to effectively deplete the reservoir.
Many advances in the drilling and completing of well bores have allowed for production of deep reservoirs. Further, well bores are becoming highly deviated which allow for the reaching of isolated reservoirs. Also, horizontal wells drilled through a productive zone allow for maximum production.
Various devices have been devised in order to obtain bottom hole pressures. Many of these devices are lowered into the well bore via wire line. The tool string may comprise a bottom hole pressure gauge, which can be a quartz type, with memory capability. Other types of work strings for positioning bottom hole pressure assemblies are possible such as coiled tubing, electric line, and braided line.
During the course of obtaining a bottom hole pressure, operational problems may occur. Many times the work string, such as the wire line, becomes entangled and the line breaks. Once the line breaks, the bottom hole assembly falls to the bottom of the well bore. Thereafter, costly retrieval operations (sometimes referred to as "fishing" operations) must be undertaken in order to retrieve the assembly, and many times the bottom hole assembly is lost. Thus, since the pressure and memory gauges are quite costly, the lost of these tools is highly undesirable. Also, the information collected is also lost.
Further, operators will many times require a flowing bottom hole pressure measurement. Thus, the bottom hole assembly is retrieved from the well bore with the reservoir actually producing reservoir fluids and gas. Due to the flow profile within the production tubing string, the bottom hole assembly may become suspended in the upward flow of reservoir fluids and gas which in effect causes the bottom hole assembly to be blown out of the well bore which is a very dangerous situation.
Therefore, there is a need for an apparatus that will preclude the loss of the bottom hole assembly when the wire line has broken. There is a further need for a device that will preclude the bottom hole assembly from being blown out the well bore.